Fragmentation casing and method of making

ABSTRACT

The fragmentation casing has a one-piece hollow body (1) that incorporates nominal break points; this hollow body (1) is divided at least in one section (4) by at least one separating cut (5) that forms a separating gap. The separating cut is so made that the hollow body remains in the form of a one-piece structure. The surfaces of the separating cut that are adjacent in the separating gap are brought into contact with each other and are so fixed in contact with each other.

TECHNICAL DOMAIN

The present invention relates to a fragmentation casing for an explosivedevice, in particular for a projectile, a grenade, or a mine, with aone-piece hollow body that incorporates nominal break points. Inaddition, the present invention relates to a process for the productionof such a fragmentation casing.

PRIOR ART

It is known that projectiles, grenades, or mines can be fitted with afragmentation casing that is configured as a hollow body that containsan explosive bursting charge and which, on detonation, is intended toshatter into the greatest possible number of fragments. In order tofacilitate this fragmentation, the fragmentation casing usuallyincorporates nominal break points If, however, these nominal breakpoints are in the form of grooves in the fragmentation casing, some ofthe potential total mass of the fragmentation casing (in relation to itssize) is lost. The following methods, amongst others, have been used inorder to avoid this mass decrement, at least in part:

In order to produce a fragmentation casing, wire of squarecross-section, as well as with previously made notches transverse to itslongitudinal axis on one (EP-B1-0 030 809) or two (US-H238) sides hasbeen wound into a spiral such that the coils so formed were closelyadjacent, so that there was no gap between them and no mass was lost.The coils were then joined to each other by soldering (EP-B1-0 030 809)or by laser welding (US-H328). DE-OS 32 21 ,565 also describes a spiralfragmentation casing. DE-U1-84 27 962.1 describes a fragmentation casingthat consists of rings of rectangular cross-section that are arranged ona supporting body instead of being closely adjacent. DE-U1-84 27 781.5describes a warhead with cracks in the warhead housing that result fromgrooves machined into the wall of the warhead housing, by upsetting thewarhead housing.

However, the production of all the above types of fragmentationhousings, in particular those with rings, is extremely costly.

DESCRIPTION OF THE INVENTION

It is the task of the present invention to describe a fragmentationcasing of the type described heretofore, it being possible to producethis with far less labour and in a more rational manner.

According to the present invention, this task has been solved by afragmentation housing having the distinguishing features set forthbelow. The underlying concept of this solution is that the hollow bodyis slit in at least one section by at least one separating cut thatforms a separating gap, the separating cut being so made that the hollowbody remains as a one-piece structure. The surfaces of the separatingcut that are adjacent in the separating gap are brought into contactwith each other and then fixed when in contact with each other.

Advantageous and preferred embodiments of the present invention are setforth below.

Additionally, it is the task of the present invention to describe aprocess that is particularly suitable for the production of such afragmentation housing.

This task has been solved by a process as described below.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described below on the basis of examples shown in thedrawings appended hereto These drawings show the following:

FIG. 1: A hollow body in the form of a hollow cylinder, the casing ofwhich is divided equally into coils between two end sections by aseparating cut, said coils being spaced by being drawn apart from eachother.

FIG. 2: A hollow body as in FIG. 1, this being compressed, however, sothat the coils rest against each other.

FIG. 3: A cross-section through a hollow body as in FIG. 2, in which,however, the adjacent edges of the separating cut are partially joinedto each other by welding on the outer periphery.

FIG. 4: A hollow body as in FIG. 2, but in which the adjacent edges ofthe separating cut are partially connected to each other bydiscontinuous welding on the outer periphery.

FIG. 5: A cross-section through a hollow body as in FIG. 2, but with asupporting sleeve inserted therein.

FIG. 6: A cross-section of a hollow body, only half of which is shown,in which, however, the separating cut is for the most part inclined atan oblique angle to its surface.

FIG. 7: A hollow body as in FIG. 2, in which, however, sections of theseparating cut are in a zig-zag form.

FIG. 8: A hollow body as in FIG. 2, in which, however, the separatingcut is formed so as to produce an interlocking effect.

FIG. 9: A cross-section of a hollow body as in FIG. 2, only half ofwhich is shown, in which, however, the spacing of the coils is notconstant.

FIG. 10: A hollow body as in FIG. 2, in which, however, there are twoseparating cuts.

FIG. 11: A hollow body as in FIG. 2, in which, however, there is ablocked-on detonator head.

FIGS. 12 and 13: Cross-sections through hollow bodies in the form ofhollow cylinders, on the inner or outer walls of which there are groovesthat extend axially, to form nominal break points.

METHODS OF REDUCING THE INVENTION TO PRACTICE

In the drawings, the invention will be described on the basis of ahollow cylinder 1 as a hollow body. This hollow cylinder is producedfrom a metallic material, for example, heat-treated steel. Reference isfirst made to FIG. 1. The hollow cylinder 1 shown therein is of aconstant wall thickness. There is a helical separating cut 5 in thecenter section 4 that is located between the two end sections 2, 3, thecenter section 4 being formed into coils 6 thereby. This separating cut5 is produced by a metal-cutting apparatus, for example, a laser or aplasma cutting system. The separating cut 5 can also be produced byother means, for example, by a mechanical cutting system. In FIG. 1, thegap that is formed between the coils is shown enlarged as a result ofthe coils 6 having been drawn apart. In actual fact, the width of thegap produced when the separating cut is made by a laser cutting systemis only approximately 0.15 to 0.3 mm.

Despite the small gap width that can be achieved, the mass decrementassociated therewith is considered undesirable. This mass decrement can,however, be eliminated very simply by compressing the cylinder 1. FIG. 2shows the hollow cylinder as in FIG. 1, albeit with the coils 6compressed so that they abut closely against one another, therebyproducing a continuous, compact, hollow cylinder.

In order to facilitate this compression at the two ends of theseparating cut as well, a small hole 7 of at least approximatelycircular cross-section can be produced at each end.

In the compressed state, the hollow cylinder 1 is under a certain amountof elastic tension. In order that it remain thus, it has to be fixed inthis state. This can be effected in a very simple manner by weldingadjacent edges of the separating cut 5 together, as is shown in FIG. 5.In FIG. 3, a welded seam on the outside periphery, which extendscontinuously along the separating cut, is numbered 8.

FIG. 3 shows an embodiment of the invention in which the edges of theseparating cut 5 are discontinuous welded along the separating cut, onthe outside periphery. The individual discontinuous welds are numbered9.

In principle, it is possible, albeit more difficult from the technicalstandpoint, to make such welds on the inside, either as an alternativeor in addition to welds made on the outside.

A body that is stable per se can be produced from the hollow cylinderthat has been intersected by the separating cut by the welds made on theedges of the separating cut, and such a body is immediately suitable foraccommodating an explosive charge, without needing any additionalreinforcing or strengthening elements.

Another possible way of fixing the hollow cylinder in the compressedstate is by using a supporting sleeve. FIG. 5 illustrates theincorporation of an interior supporting sleeve. In the right-hand partof FIG. 5, the hollow cylinder 1 is fixed at one end by a shoulder 11 ofthe supporting sleeve 10, which extends outwards; the left-hand part ofFIG. 5 shows the other end fixed by a rim on the supporting sleeve 10that fits in an inside groove 12 in the hollow cylinder. It is preferredthat the supporting sleeve 10 be of a metal that is relatively amenableto shaping, such as aluminum, and is press fitted into the hollowcylinder (whereby the metal flows into the groove in the hollowcylinder). The supporting sleeve can also be in the form of an externalsleeve (not shown herein).

The stability of the hollow cylinder 10 is greatly enhanced by thesupporting sleeve 10. However, the supporting sleeve 10 requires acertain volume, by which the volume of the explosive charge that is tobe contained within the cylinder must be reduced. For this reason, thesolution that involves welding is to be preferred in regard to theoptimal relationship between the size of the explosive charge and thetotal mass of the explosive device.

FIG. 6 is a half cross-section of a hollow body as in FIG. 2; in thisexample, however, the separating cut is for the most part made at anobtuse angle to the surface of the hollow body. This makes it possible,for example, to take into account the manner in which the shock wave,generated when the explosive charge is detonated, is distributed inspace.

FIG. 7 shows a hollow body as in FIG. 2, in which however, theseparating cut 5 is in the form of zig-zag or serpentine sections.Meshing of the individual coils 6 with each other, which increases thestability of the hollow body, is achieved by such a configuration of theseparating cut 5.

The same applies to the embodiment shown in FIG. 8, in which theseparating cut 5 is made in sections such that the areas of the hollowbody 1 that are located on both sides of the separating cut areadditionally interlocked with each other.

FIG. 9 is a half cross-section of a hollow body as in FIG. 2; in thisexample, however, the pitch of the coils 6 is not constant, butdecreases from the middle 4 towards each end (towards the end sections2, 3). This, too, makes it possible to take into account the manner inwhich the shock wave, generated when the explosive charge is detonated,is distributed in space.

Even though only one separating cut is to be preferred, it is of coursepossible to incorporate a plurality of such separating cuts. FIG. 10shows a hollow body 1 as in FIG. 2, in which two helical separating cuts5, 5', which do not intersect, have been made. In addition, theseparating cuts can be so made as to be interrupted instead of beingwelded (8 or 9 in FIGS. 3 or 4, respectively).

FIG. 11 shows a fragmentation casing that is configured as apredominantly cylindrical sleeve 13 with a base 14 that is formed as anattachment element for a detonator head. Such a hollow body is producedby hot and/or cold massive forming or by a drawing and ironing processprior to the production of the separating cut, when the attachmentelement for the detonator head is blocked out at the same time. Theseparating cut 5 ends or begins a short distance from the opening at theleft-hand side of the sleeve, on the one hand, and from its base 14, onthe other.

FIGS. 12 and 13 show cross-sections of hollow bodies in the form ofhollow cylinders, in the inner or outer walls of which there are axialgrooves 15 or 16 that taper to points, these grooves acting as nominalbreak points. If the above production techniques cited heretofore areused, the grooves can be formed at the same time. Instead of extendingaxially, the grooves can also extend helically, for example. Generallyspeaking, they should be substantially perpendicular to the separatingcuts.

The embodiment of the hollow body is in no way confined to the form of ahollow cylinder. The invention can be applied without any problem toconical, truncated conical, spherical, ovoid, plate-shaped, orgrenade-shaped hollow bodies, with one embodiment being possible with orwithout a supporting sleeve. Hollow bodies that are open at twolocations, at only one location or on only one side, or are completelyclosed can be used.

If the grooves that produce the nominal break points are omitted, theresulting hollow body with its coil section can be used for otherpurposes, for example, after appropriate heat treatment, as a spring.All materials in which a separating cut can be produced by a suitableprocess can be used.

I claim:
 1. A fragmentation casing for an explosive device, saidfragmentation casing comprising a one-piece hollow body (1), saidone-piece body having a cylindrical portion (13) and a base portion(14), said cylindrical portion having inner and outer cylindricalsurfaces, one of said inner or outer cylindrical surfaces being groovedto provide nominal break points upon explosion of the explosive device,a section of said cylindrical portion having at least one cut defined byfirst and second opposing surfaces, said cut extending in asubstantially helical form along said section, said first opposingsurface being substantially in engagement with said second opposingsurface, said base portion being disposed at and closing one end of saidcylindrical portion, said base portion being configured as an attachmentelement for a detonator head, and said cut extending to a point on saidcylindrical portion located a short distance from said base portion. 2.A fragmentation casing as set forth in claim 1, further comprising meansfor maintaining said first opposing surface in engagement with saidsecond opposing surface.
 3. A fragmentation casing as set forth in claim2, wherein said means for maintaining includes welding along at least aportion of said cut.
 4. A fragmentation casing as set forth in claim 2,wherein said means for maintaining includes a hollow supporting memberinserted into said cylindrical portion.
 5. A fragmentation casing as setforth in claim 1, wherein said body has at least one open end, said cutextends to a point on said cylindrical portion located a short distancefrom said open end.
 6. A fragmentation casing as set forth in claim 1,wherein an end of said cut extends to a hole that is approximately roundin cross-section.
 7. A fragmentation casing as set forth in claim 1,wherein the helical form of said cut has a slope which varies.
 8. Afragmentation casing as set forth in claim 1, wherein said cut extendssuch that at least a portion of said first and second opposing surfacesinterlock.
 9. A fragmentation casing as set forth in claim 1, whereinsaid cut includes a zig-zag portion.
 10. A fragmentation casing as setforth in claim 1, wherein said cut includes a serpentine section.
 11. Afragmentation casing as set forth in claim 1, wherein said first andsecond opposing faces are substantially perpendicular to said inner andouter cylindrical surfaces.
 12. A fragmentation casing as set forth inclaim 1, wherein a portion of each of said first and second opposingfaces is inclined at an obtuse angle to said inner and outer cylindricalsurfaces.
 13. A fragmentation casing as set forth in claim 1, saidsection of said cylindrical portion including a plurality of cuts, eachof said plurality of cuts being defined by first and second opposingsurfaces, each of said cuts extending in a substantially helical form,each of said plurality of cuts being nonintersecting with the other ofsaid plurality of cuts.
 14. A method of making a fragmentation casing,said method comprising the steps of:forming a one-piece hollow body, thehollow body having a cylindrical portion with inner and outer surfacesand a base portion, said base portion being disposed at and closing oneend of said cylindrical portion, said base portion being configured asan attachment element for a detonator head; forming grooves on one ofsaid inner and outer surfaces of the cylindrical portion; cutting ahelical cut defined by first and second opposing surfaces along at leasta section of the cylindrical portion; and engaging the first opposingsurface to the second opposing surface.
 15. A method as set forth inclaim 14, wherein said step of cutting is performed with a laser.
 16. Amethod as set fort in claim 14, including the step of attaching a meansfor maintaining the first opposing surface to the second opposingsurface.
 17. A method as set forth in claim 16, where said step ofattaching a means for maintaining the first opposing surface to thesecond opposing surface includes welding.
 18. A method as set forth inclaim 16, wherein said step of attaching a means for maintaining thefirst opposing surface to the second opposing surface includes insertinga hollow supporting member into the cylindrical portion.
 19. A method asset forth in clam 14, wherein said step of forming a one-piece hollowbody includes drawing and ironing a material into the shape of thecylindrical portion and the base portion.